The Evolution and Role of <scp> <scp>NH</scp> </scp> ₄ <scp> <scp>Cl</scp> </scp> Flux Used to Synthesize <scp> <scp>Sr</scp> </scp> ₂ <scp> <scp>SiO</scp> </scp> ₄ : <scp> <scp>Dy</scp> </scp> ³⁺ Phosphor by Solid‐State Reaction Method

Abstract

Two different Sr 2 SiO 4 : Dy 3+ phosphors were successfully synthesized at 1000°C for 4 h using NH 4 Cl or SrCl 2 as the flux, respectively. The luminescence intensity of Sr 2 SiO 4 : Dy 3+ was enhanced 60 times by the addition of 5 wt% NH 4 Cl . The phase evolution and photoluminescence (PL) properties of the phosphors were investigated by the calculation of phase equilibrium and the analysis of TG / DSC , XRD , SEM , and PL . The role of NH 4 Cl was proved to be attributed to the formation of SrCl 2 at ~300°C. The flux NH 4 Cl or SrCl 2 lowered the decomposition temperature of carbonate and promoted the preferential formation of α′ phase in the solid‐state reaction through accelerating the kinetics of the formation of Sr 2 SiO 4 by enhancing diffusion with more liquid phase.